Fix missing impermanence module import.

nodes/hosts/nixy/configuration.nix

@@ -2,11 +2,12 @@
 # your system. Help is available in the configuration.nix(5) man page, on
 # https://search.nixos.org/options and in the NixOS manual (`nixos-help`).
 
-{ config, lib, pkgs, ... }:
+{ config, lib, pkgs, inputs, ... }:
 
 {
   imports =
     [ # Include the results of the hardware scan.
+      inputs.impermanence.nixosModules.impermanence
       ./hardware-configuration.nix
       ./impermanence.nix
       ./programs/streamcontroller.nix